As magnetic media disks are manufactured, they are repeatedly loaded and unloaded onto texturizing equipment for texturizing the surfaces of the disks. Generally speaking, a robotic assembly associated with this texturizing equipment repetitively retrieves individual untexturized disks from a cassette holding a plurality of untexturized disks spaced apart in horizontal axial alignment. The robotic assembly transports the untexturized disk to the texturizing equipment and mounts it on a collet for texturization. After texturization, the robotic assembly grips the mounted individual texturized disk from the collet and returns it to the cassette.
The robotic assembly grips the disk with a gripper apparatus. The gripper apparatus typically comprises a plurality of actuatable fingers disposed about a face to engage the outer circumferential surface of a disk. To grip a disk, the robotic assembly moves the gripper into axial alignment with the disk so that the gripper face is parallel to one of the flat disk surfaces. The robotic assembly moves the gripper towards the disk along the disk axis until the gripper fingers are circumjacent to the outer circumferential surface of the disk. The gripper fingers then close to grip the disk. When the gripper fingers are closed about the outer circumferential surface of the disk, the disk may be transported. To improve the efficiency with which disk texturizing equipment loads and unloads disks, the robotic assembly typically includes two grippers, one for loading disks onto the texturizing equipment and one for unloading disks from the texturizing equipment.
As stated above, the robotic assembly mounts untexturized disks onto a collet on the texturizing equipment. The robotic assembly transports the untexturized into axial alignment with the collet on the texturizing equipment. The robotic assembly moves the untexturized disk forward until the inner circumferential surface of the disk is circumjacent to the collet. An electromechanical system in the texturizing equipment expands the collet to radially clamp the inner surface of the disk. The gripper is opened to release the disk and the robotic assembly is retracted. The texturizing equipment rotates the collet which in turn rotates the disk for texturization.
The process of mounting the disk on the collet is of particular concern. Problems have arisen in light of the need to pack more and more information on each magnetic disk, which has resulted in the utilization of the entire disk surface for memory storage. As a result, the integrity of the entire surface of the disk, including the inner portions close to the opening in the middle of the disk is essential. Any misalignment of the disk while being mounted on the collet may cause the inner circumference of the disk to contact the collet. Such collisions may cause undesirable dents or scratches in the disk.
The problem is exacerbated by the ever-present demand for smaller and lighter memory storage devices. As a result, the thickness of the magnetic media disks has decreased. For example, where as a 3.5" diameter, 500MB disk used to have a thickness of about 0.050", a disk with the same diameter and capacity is now typically less than 0.025" thick. Therefore, these disks are increasing more delicate and susceptible to dents.
Most disk mounting systems according to the prior art rely entirely on the accuracy of the robotic assembly to mount the disks. As stated above, these systems employ grippers that include a plurality of expandable fingers around the outer circumference of the disk to grip the disk from the disk cassette. After the disk is gripped, the robotic assembly rotates into a position where the center of the disk is aligned along the axis of the collet on the texturization equipment. Once in this position, the robotic assembly translates forward to until the inner circumference of the disk circumscribes the outer circumference of the collet.
There are a number of problems with such prior art systems. There is only approximately 7.5 thousandths of an inch difference between the radius of the opening of the disk and the collet. When there is a misalignment between the axis of the disk and the axis of the collet of greater than 7.5 thousandths of an inch, these systems must use the opening in the middle of the disk to guide the disk onto the collet. In other words, the inner circumferential surface hits the collet and bounces the disk into alignment. As stated above, all such contact is undesirable because the integrity of the entire disk surface is essential.
This problem is exacerbated by the need to process more disks in less time. As a result, the industry uses ever faster robotic assemblies to cycle disks through each texturization process. High speed rotation of these robotic assembly generates high magnitude moments, which in turn produce oscillatory motion. This oscillatory motion in the robotic assembly makes proper alignment during mounting significantly more difficult.
In order to minimize the alignment problems, the industry has been forced to employ extremely expensive, complex and delicate robotic assemblies. Even with these systems, disks still tend to get dented or scratched during mounting. In addition, complex robotic assemblies are susceptible to breakdown.
Alternative prior art disk mounting systems employ one or more guide pins projecting out from the gripper face along an axis perpendicular from the face. These guide pins work in cooperation with one or more guide holes located on the disk texturizing equipment adjacent to the collet in a male/female relationship. Typically the guide pins have a tapered nose section so that when initial positioning of the gripper is slightly off-center the guide pins still fit into the guide holes.
There are a number of disadvantages associated with this type of prior art disk mounting system. A degree of inaccuracy is introduced because the aligning guide holes are offset from target collet. Precise placement of the guide holes and guide pins is important since any variance between the guide hole or guide pin position and the collet will result in misalignment of the disk during mounting. Such precise placement requires added complexity and expense to the overall system.
Additionally, the slightest displacement of the collet or bending of the guide pins will result in repeated misalignment of the disk during mounting. Moreover, the guide pins add additional weight to the robotic assembly. Therefore, the problem associated with high speed rotation of these robotic assembly (i.e. producing oscillatory motion) is magnified.
Note that a range of motion must be provided by the gripper when using tapered guide pins to compensate for inaccuracies in the initial alignment of the gripper. As the guide pins are fastened to the gripper face, typically the entire gripper subassembly moves during alignment. The speed at which disks can be mounted is limited by the mass required to move during alignment of the disk. As gripper subassemblies used in tapered guide pin and hole mounting systems are relatively complex and massive, this represents a further disadvantage of these systems.
An additional disadvantage associated with each of the prior art disk mounting systems described above is disk damage occurring along the outer circumferential surface of the disk. The damage results from the actuation of the actuatable gripper fingers. As described above, the industry is using smaller and lighter disks in memory storage devices and these disk are more susceptible to dents.
It is therefore an object of the invention to provide a simple and inexpensive apparatus for accurately mounting disks on disk texturizing equipment that avoids using the inner circumference of the disk as a guiding element.
It is a further object of the invention to provide an apparatus for accurately mounting disks on disk texturizing equipment that does not rely solely on the accuracy of the robotic assembly.
It is a further object of the invention to provide a simple and lightweight guiding apparatus that uses a guiding means which simply and inexpensively may be positioned relative to the collet.
It is a further object of the invention to provide an apparatus for accurately mounting disks on disk texturizing systems which provides a range of motion in the disk during alignment of the disk, without excessive weight which must be moved along with the disk, thereby allowing high speed disk mounting.
It is a further object of the invention to prevent dents or scratches from occurring at the outside circumference of the disk when gripped by the gripping apparatus.